This is a continuation-in-part application from a copending U.S. patent application Ser. No. 07/118,403 filed Nov. 9, 1987, now aband, which is a continuation application of a now abandoned U.S. patent application Ser. No. 06/853,615 filed Apr. 18, 1986.
The present invention relates to a heat-resistant anti-glare screen or, more particularly, to an anti-glare screen having good heat resistance suitable for mounting in front of various kinds of light-emitting display screens with an object to enhance the contrast and visibility of the displayed images and to reduce glaringness of the images to the viewer's eyes with adjustability of the visual angle.
An anti-glare screen having adjustability of the visual angle can be well comprehended when one imagines a venetian blind having a number of vanes arranged at a variable angle and installed on a window so as to shield the sun light most effectively by appropriately rotating the vanes. Apart from such devices used in buildings, a problem of glaringness is sometimes encountered in various kinds of display units such as cathode-ray tube screens and metering instruments giving information with luminescent images. Accordingly, several types of anti-glare or light-shielding screens have been proposed including those made of a sheet of cellulose acetate butyrate provided with a large number of minute vanes like louvers. When such a screen is mounted in front of the display unit, incidence of extraneous outer light on the display screen is partially shielded within a range of angles so that the visibility of the display screen can be improved.
The above mentioned conventional anti-glare screen made of a sheet of cellulose acetate butyrate are disadvantageous due to their relatively low heat resistance so that they are subject to deformation or emission of gases having unpleasant odor when they are heated at a temperature of 70.degree. to 80.degree. C. or higher. For example, it is not rare that the room temperature of an automobile in long parking under direct sun light as in a tropical climate is increased to exceed the above mentioned temperature so that the anti-glare screen mounted on the metering instruments of the automobile may undergo or cause the above mentioned drawbacks. These drawbacks can be eliminated by replacing the sheet of cellulose acetate butyrate with a plate of an acrylic resin though at the sacrifice in other respects such as blooming of white dusts on the surface during use and the relatively large thermal expansion coefficient of 14.times.10.sup.-5 /.degree.C. to cause a decrease in the dimensional stability at elevated temperatures.
When an anti-glare screen of a conventional type is attached to the front glass of a cathode-ray tube (CRT), a disadvantage is sometimes caused that a phenomenon of so-called Newton's rings appears to greatly decrease the visibility of the images displayed on the CRT screen. This problem is presumably due to the fact that the surface of the front glass of CRTs usually and unavoidably has certain irregularities or is warped so that perfectly intimate contact can rarely be obtained between the CRT screen and the anti-glare screen mounted thereon.